This invention relates to a novel process for producing hydrogen and sulfur from hydrogen sulfide. More particularly, the process is a novel method for accomplishing the thermal decomposition of hydrogen sulfide at temperatures between about 982.degree. C. and about 1816.degree. C.
Hydrogen sulfide is found in various industrial streams. For example, hydrogen sulfide is produced during coal gasification and liquefaction, and hydrogen sulfide is produced in petroleum refining of sulfur bearing crudes. Hydrogen sulfide is also present in various proportions in sour natural gas which is found throughout the world.
The primary commercial method for processing hydrogen sulfide that is employed by industry is the well-known Claus process. The Claus process is an oxidation-reduction process which produces only sulfur and water.
It is known to the art that at elevated temperatures hydrogen sulfide is partially decomposed into hydrogen and sulfur as indicated by the following formula: EQU H.sub.2 S.fwdarw.H.sub.2 +1/2S.sub.2
In recent years, the possibility of converting hydrogen sulfide into hydrogen and sulfur via thermal decomposition techniques has received much attention. In an article entitled "Make Hydrogen From Hydrogen Sulfide" (Hydrocarbon Processing 139-142, 1975), M.E.D. Raymont discusses the desirability of producing hydrogen and sulfur via thermal decomposition processes. Raymont discusses the possibility of employing various metal catalysts to drive the reaction so that moderate process conditions (i.e., lower temperatures) can be employed which will result in a sufficient conversion of hydrogen sulfide into hydrogen and sulfur. Additionally, Raymont describes two processes that employ the oxidation of carbon as the source of negative free energy change required to bring about the reaction.
U.S. Pat. No. 3,962,409 (Kotera et al., 1976) discloses a method for producing hydrogen and sulfur from hydrogen sulfide by contacting hydrogen sulfide with a catalyst selected from the group consisting of molybdenum sulfides, tungsten sulfides, and ruthenium sulfides at a temperature between about 450.degree. C. and about 800.degree. C.
U.S. Pat. No. 4,302,434 (Hellmer et al., 1981) discloses a method for thermally decomposing hydrogen sulfide into hydrogen and sulfur at temperatures between about 850.degree. C. and about 1600.degree. C. Hellmer et al. achieves the high temperatures necessary to effect the decomposition by either indirect heat exchange or more direct means by the combustion of a fuel in the decomposition chamber.
It is an object of the present invention to provide a commercially viable process for the thermal decomposition of hydrogen sulfide into hydrogen and sulfur. Our process does not require the aid of a catalyst. Our process achieves the decomposition of hydrogen sulfide by employing high temperatures in order to closely approach thermodynamic equilibrium. In the preferred embodiments of the invention, a portion of the sulfur that is produced by the process is combusted in the presence of an oxygen containing gas to produce hot gases that are employed to heat a decomposition reaction chamber to the required temperature profile.